The orbital portion of the lacrimal gland is located in the superotemporal orbit and the palpebral portion of the lacrimal gland is located on the posterior surface of the superotemporal upper lid. The lacrimal gland produces the aqueous portion of the tear film. Ductules from the orbital portion of the lacrimal gland pass through the adjacent palpebral lacrimal gland to empty in the superior conjunctival cul-de-sac. Smaller accessory lacrimal glands in the upper and lower lids also contribute to tear production. The tears bathe the surface of the eye and then drain into the nose via the lacrimal drainage system.
Referring now to FIGS. 1 and 2, the lacrimal drainage system comprises a pair of small openings, namely the superior punctum 2 and inferior punctum 3, are located on the medial upper and lower lids of the eye 1. Tears flow into these puncta which lead to two small diameter delicate tubes, namely, the superior canaliculus 4 and the inferior canaliculus 5. The canaliculi join together as a short common canaliculus 6 that enters into the larger lacrimal sac 7. The tears then flow from the lacrimal sac down the nasolacrimal duct 8 and out an opening 9 which empties into the nose on the lateral nasal wall 10 and on to the nasal floor 11 beneath the inferior turbinate 12. This space beneath the inferior turbinate is called the inferior meatus 13 of the nasal cavity.
The canaliculi can become obstructed or stenotic on a congenital basis, or acquired as a result of some trauma such as lacerations, inflammation, side effects of chemotherapy, such as taxotere or five-fluorouracil—which may also affect the nasolacrimal duct—or the obstruction can be idiopathic. Once obstructed, tears can no longer drain from the surface of the eye through the lacrimal drainage system into the nose. As a result tears well up in the eye, and run down the face. Excess tears blur the vision and the patient has to constantly dab the eye.
The nasolacrimal duct can be obstructed on a congenital basis, occurring in about 2% to 6% of newborns, or acquired as a result of some trauma, sarcoidosis or other diseases, but most commonly is idiopathic. When the nasolacrimal duct is obstructed, tears stagnate in the lacrimal sac where bacteria multiply leading to infection. The result is a painful enlargement of the lacrimal sac swollen with pus, and a discharge over the eye.
A congenital nasolacrimal duct obstruction often resolves spontaneously, or with the use of antibiotic drops and massage of the lacrimal sac. However, a significant number of patients require surgical treatment.
Canalicular obstruction or stenosis, and nasolacrimal duct obstructions are often treated by forming a passageway through the obstruction or stenotic tissue using a surgical probe which is a small diameter, blunt-ended rod made of solid steel, bronze, silver or other metal. A flattened area in the center of the probe facilitates its manipulation.
The passageway through the nasolacrimal duct can be further dilated using a balloon catheter through dacryocystoplasty (DCP). Often the treatment of nasolacrimal duct obstruction in adults involves the creation of a new passage from the lacrimal sac directly into the nasal cavity bypassing the nasolacrimal duct according to a procedure called dacrocystorhinostomy (DCR). Both procedures are disclosed in my U.S. Pat. No. 5,169,386 incorporated herein by this reference.
Intubation or stenting of the lacrimal system is often performed after lacrimal surgery or as a primary treatment for nasolacrimal duct obstruction, canalicular stenosis, or canalicular laceration, in order to keep the lacrimal drainage passageway open and prevent scars from permanently clogging the canaliculi or nasolacrimal duct.
In this specification the term “intubation” is meant to include the insertion of both tubular and non-tubular oblong flexible devices into the lacrimal drainage system in order to keep the passageway open regardless of whether tears flow through a tubular device or around a non-tubular device. Since tears typically flow around the device whether it is tubular or not, the term “stent” in this specification is used to collectively refer to a tubular or non-tubular device remaining inserted in the lacrimal drainage system after an intubation process has been performed.
In cases of canalicular or nasolacrimal duct obstruction from chemotherapy, intubation is performed as quickly as possible to prevent complete, irreversible closure. Intubation typically involves placement of a flexible silicone tube looped through both canaliculi where both ends extend down the nasolacrimal duct and into the nose. Such intubation is described in Martinez, U.S. Pat. No. 4,305,395, and Crawford et al., U.S. Pat. No. 4,380,239, both of which are incorporated herein by this reference.
A number of types of intubation devices are available. The most common type is a silicone tube having a metal probe attached on each end as in Crawford et al. cited above. A probe on one end is pushed through one of the punctum, its canaliculus, the lacrimal sac, and down the nasolacrimal duct into the nose. The probe is grasped in the nose by the surgeon and pulled out the naris. The tube follows the probe. The probe on the other end of the tube is pushed through the second punctum, its canaliculus, the lacrimal sac, and down the nasolacrimal duct into the nose, grasped by the surgeon, and pulled out the naris bringing the other end of the tube with it. The probes are removed and the two ends of the tube are tied together and left hanging in the nose. The tube is removed several months later by pulling it up the lacrimal system, cutting it, and removing it through one of the puncta.
The above process presents several difficulties. First, the nasal opening to the nasolacrimal duct is extremely difficult to visualize during surgery or examination, and very difficult to access with an instrument, making the grasping of the probe difficult. Rigid and flexible endoscopes usually cannot fit between the inferior turbinate and the lateral nasal wall. Direct visualization using a nasal speculum and a headlight is usually not possible. Placing an instrument near the nasolacrimal duct opening through the nose can be very difficult. A probe or tube sticking out of the nasolacrimal duct opening in the nose will often be buried in the surrounding soft tissue of the nasal floor or lateral wall. Further, there is often edema of the inferior turbinate and nasal mucosa, and sometimes bleeding which make it more difficult to locate, access, grasp, and retrieve the probe, tube, suture or other item coming out of the nasolacrimal duct opening. It is often difficult if not impossible to position a suction catheter in the inferior meatus in order to remove blood around the nasolacrimal duct opening.
One way of trying to confirm without visualization whether the probe, tube or other item has penetrated into the nose is by touch. The surgeon will typically introduce a metal instrument through the external naris into the nose and try blindly to touch the tip of the item sticking out of the nasolacrimal duct opening until a contact between the two is felt. Detecting contact takes quite a bit of skill and experience. Often, if no contact is felt, the surgeon may remove the item and reinsert it, then try again to confirm penetration. These repeated procedures can cause multiple traumas to the lacrimal drainage system.
Another commonly used intubation device is the MINI-MONOKA device available from FCI Ophthalmics Inc. of Marshfield Hills, Mass. (hereinafter “FCI”). This device consists of a short silicone tube which is generally not long enough to extend into the nasolacrimal duct. The proximal end of the tube is formed into a punctal plug to anchor it in a punctum. The tube is threaded through a punctum and canaliculus into the lacrimal sac, and can be used to stent the canaliculus but typically not the nasolacrimal duct.
Another type of intubation device is the MONO-CRAWFORD device available from FCI which is similar to the MINI-MONOKA device but provides a longer flexible stent. It also has a punctal plug at its proximal end. The distal end must be threaded through the lacrimal system from the eye side but is too flexible to be pushed on its own through the system.
The RITLENG probe, also available from FCI, has been designed to help this problem. It is a hollow metal guide tube with a slit-like opening along its entire length which is placed through the punctum, canaliculus, lacrimal sac, and down the nasolacrimal duct into the nose. A separate polyethylene tube that is attached to a flexible silicone tube having a punctal plug formed on its proximal end is threaded through the guide into the nose. The polyethylene tube is located and grasped in the nose by the surgeon and pulled out the naris. The guide is then withdrawn out the punctum. The silicone tube passes through the slit so that the guide can be removed. The plug on the proximal end of the silicone tube is then seated in the punctum. The distal end of the silicone tube is then cut just inside the external naris. Therefore, the RITLENG tube must be retrieved and pulled out the nose. This can be difficult or impossible in some cases as detailed above.
Both the MINI-MONOKA and RITLENG devices use punctum plugs integrally formed onto the proximal ends of flexible tubes. Therefore, the length of the tube can only be altered during surgery by cutting the distal end. The RITLENG and MONO-CRAWFORD tubes must be retrieved in the nose and brought out the nose to achieve this. The MINI-MONOKA tube is too short to have its length altered in vivo.
My U.S. patent application Publication No. 2007/0276314 incorporated herein by this reference describes a silicone tube with a balloon on the end. It extends from the punctum and canaliculus into the lacrimal sac. A balloon on the end of the tube in the lacrimal sac is then inflated to keep the tube in position. The tube does not extend into the nasolacrimal duct.
The FCI company has a plug that is placed in the punctum in order to obstruct the punctum and prevent tear drainage through the lacrimal system into the nose. This is used for patients with dry eye syndrome to keep more tears in the tear film over the eye. The FCI plug has a lumen with a proximal opening and a distal closed end. A metal probe at the end of an inserter stretches the tube along its longitudinal axis to reduce the diameter during insertion. When the plug is in place, the inserter is withdrawn and the plug contracts along its longitudinal axis and thus increases radially so that it will be snug in the punctum and not fall out. The lumen does not expand. The device is not expanded radially by the inserter, but rather is expanded longitudinally which decreases its outside and inside diameter.
I show in International Publication No. WO 2007/139919 a lacrimal stent that uses a soft tube, ideally silicone, that has a higher durometer reinforcer tube within the closed distal end. The silicone stent can be placed in the lacrimal system through the punctum, canaliculus, common canaliculus, lacrimal sac, and nasolacrimal duct into the nose. The silicone tube and reinforcer have holes in the sidewalls in the distal end. A hollow irrigating probe having holes in the sidewalls is used to push the silicone tube into the lacrimal system and the distal end into the nose. The irrigating probe allows fluorescein stained fluid to be irrigated through the tube and recovered in the nose to confirm that the silicone tube has penetrated all obstructions and reached the nasal cavity. The reinforcer resists the probe puncturing the distal end of the silicone tube. The silicone tube does not need to be retrieved in the nose.
There are however, certain problems that have been encountered. If there is a very tight nasolacrimal duct or canaliculus, then the probe may still puncture through the end of the silicone tube and reinforcer or otherwise rupture the tube. In this event it is impossible to emplace the silicone tube in the lacrimal system.
Another problem is that the distance from the punctum through the lacrimal system to the nasal floor is quite variable between and within age groups, and it is often difficult to predict the proper length of the stent to be used. Furthermore, the angle at which the silicone tube and enclosed probe exit the nasolacrimal duct in the nose is different among patients. The angle of exit determines where the probe and tube hit the nasal floor. This is because the nasal floor is concave upward where it comes off the lateral nasal wall. The point at which the probe and tube hit the nasal floor is a factor in determining the length of silicone tube needed. Silicone tubes of many different lengths must be available for the surgeons's use for these reasons.
The instant invention results from attempts to avoid the aforesaid problems and provide more efficient, simpler and safer devices and procedures in the treatment of nasolacrimal duct obstructions.